VIsualEyes 515/525 - Additional Information Page 30
Directional Preponderance (DP)
Directional Preponderance is a calculated value that compares the nystagmus strengths in the right beating
direction with the nystagmus strengths in the left beating direction.
The directional preponderance is given in percent [%]. The default threshold level is 30%.
Fixation Suppression Index (FI)
The fixation suppression index (FI) quantifies the ability of a patient to deliberately suppress nystagmus by
fixating on a given target. It is determined just after the peak response by switching on the fixation light within
the mask (the default protocol automatically turns on the fixation lights at the appropriate time). This time
interval is shaded in yellow on the graph.
The value for FI is represented as a percentage with the test threshold of 50% used as a cut-off value.
0% indicates perfect nystagmus suppression during fixation, 50% indicates complete failure of fixation
suppression.
Spontaneous Nystagmus Correction (SPN)
If the Spontaneous Nystagmus subtest is performed inside the Caloric test, the software can correct the
nystagmus values using the nystagmus value when the patient is laying in the supine position. If the patient
experienced nystagmus in the supine test of the Positional test or during the Spontaneous Nystagmus test,
then change the test settings to include the Spontaneous Nystagmus subtest. After the Spontaneous
Nystagmus subtest is performed, the Spontaneous Nystagmus switch will become available. The graphs will
then display the corrected x-axis for adjusting the caloric response due to the patient’s latent nystagmus.
Figure 3.5.3 Caloric summary with Spontaneous Nystagmus correction enabled
Monothermal Warm Screening Test (MWST)
If only two warm irrigation subtests are performed, the system will calculate a MWST value based on these
subtests. It is not a separate test to the caloric, but will be calculated automatically in the default protocol set
up or anytime the 2 warm caloric tests are performed as the first 2 tests.
When both warms are complete, the software will automatically generate an MWST score.
If the clinician moves on to perform cools, then the MWST score is replaced with a UW score.
The default suggested value is 30%. If the maximum result exceeds 30% then an out of threshold symbol
(red diamond) will be present for this test.
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